The present invention relates generally to the field of excavation and, more particularly, to a system and process for acquiring geological and positional data, and for controlling an excavator in response to the acquired data.
Various types of excavators have been developed to excavate a predetermined site or route in accordance with a particular manner of excavation. One particular type of excavator, often referred to as a track trencher, is typically utilized when excavating long continuous trenches for purposes of installing and subsequently burying various types of pipelines and utility conduits. A land developer or contractor may wish to excavate several miles or even hundreds of miles of terrain having varying types of unknown subsurface geology.
Generally, such a contractor will perform a limited surrey of a predetermined excavation site in order to assess the nature of the terrain, and the size or length of the terrain to be excavated. One or more core samples may be analyzed along a predetermined excavation route to better assess the type of soil to be excavated. Based on various types of qualitative and quantitative information, a contractor will generally prepare a cost budget that forecasts the financial resources needed to complete the excavation project. A fixed cost bid is often presented by such a contractor when bidding on an excavation contract.
It can be appreciated that insufficient, inaccurate, or misleading survey information can dramatically impact the accuracy of a budget or bid associated with a particular excavation project. An initial survey, for example, may suggest that the subsurface geology for all or most of a predetermined excavation route consists mostly of sand or loose gravel. The contractor""s budget and bid will, accordingly, reflect the costs associated with excavating relatively soft subsurface soil. During excavation, however, it may instead be determined that a significant portion of the predetermined excavation route consists of relatively hard soil, such a granite, for example. The additional costs associated with excavating the undetected hard soil are typically borne by the contractor. It is generally appreciated in the excavation industry that such unforeseen costs can compromise the financial viability of a contractor""s business.
Various methods have been developed to analyze subsurface geology in order to ascertain the type, nature, and structural attributes of the underlying terrain. Ground penetrating radar and infrared thermnography are examples of two popular methods for detecting variations in subsurface geology. These and other non-destructive imaging analysis tools, however, suffer from a number of deficiencies that currently limit their usefulness when excavating long, continuous trenches, or when excavating relatively large sites. Further, conventional subsurface analysis tools typically only provide an image of the geology of a particular subsurface, and do not provide information regarding the structural or mechanical attributes of the underlying terrain which is critical when attempting to determine the characteristics of the soil to be excavated.
There is a need among developers and contractors who utilize excavation machinery to minimize the difficulty of determining the characteristics of subsurface geology at a predetermined excavation site. There exists a further need to increase the production efficiency of an excavator by accurately characterizing such subsurface geology. The present invention fulfills these and other needs.
The present invention is an excavator data acquisition and control system and process for characterizing the subsurface geology of an excavation site, and for utilizing the acquired data to optimize the production performance of an excavator. A geologic imaging system and a geographic positioning system are employed to initially survey a predetermined excavation site or route. A geologic characterization unit may also be employed to enhance the geologic imaging data. The acquired data are processed to provide detailed geologic and position data for the excavation site and utilized by a main control unit to optimize excavator production performance. In one embodiment, the main control unit accesses a geologic filter database, which includes geologic profile data for numerous types of geology, when analyzing unknown subsurface geology. Removing geological filter data content corresponding to known geology from the acquired geologic imaging data provides for immediate recognition of unknown and suspect subsurface objects. The geologic imaging system preferably includes a ground penetrating radar system having a plurality of antennas oriented in an orthogonal relationship to provide three-dimensional imaging of subsurface geology. Correlation software is employed to correlate acquired geologic image data to historical excavator production performance data to characterize the structural mechanics of subsurface geology. Accurate geographic mapping of an excavation site is provided by the geographic positioning system which preferably includes a mobile transponder mounted to an excavator and a plurality of ground-based transponders. In one embodiment, signals transmitted by one or more Global Positioning System (GPS) satellites are utilized together with reference signals produced by a plurality of ground-based transponders.